| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/sunhe/incubator-teaclave/third_party/rust-sgx-sdk/sgx_rand/src/distributions/range.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>range.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../sgx_rand/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../sgx_rand/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="comment">// Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License.. |
| |
| </span><span class="doccomment">//! Generating numbers between two others. |
| |
| </span><span class="comment">// this is surprisingly complicated to be both generic & correct |
| |
| </span><span class="kw">use </span>std::num::Wrapping <span class="kw">as </span>w; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::distributions::{IndependentSample, Sample}; |
| <span class="kw">use </span><span class="kw">crate</span>::Rng; |
| |
| <span class="attribute">#[allow(clippy::needless_doctest_main)] |
| </span><span class="doccomment">/// Sample values uniformly between two bounds. |
| /// |
| /// This gives a uniform distribution (assuming the RNG used to sample |
| /// it is itself uniform & the `SampleRange` implementation for the |
| /// given type is correct), even for edge cases like `low = 0u8`, |
| /// `high = 170u8`, for which a naive modulo operation would return |
| /// numbers less than 85 with double the probability to those greater |
| /// than 85. |
| /// |
| /// Types should attempt to sample in `[low, high)`, i.e., not |
| /// including `high`, but this may be very difficult. All the |
| /// primitive integer types satisfy this property, and the float types |
| /// normally satisfy it, but rounding may mean `high` can occur. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// use sgx_rand::distributions::{IndependentSample, Range}; |
| /// |
| /// fn main() { |
| /// let between = Range::new(10, 10000); |
| /// let mut rng = sgx_rand::thread_rng(); |
| /// let mut sum = 0; |
| /// for _ in 0..1000 { |
| /// sum += between.ind_sample(&mut rng); |
| /// } |
| /// println!("{}", sum); |
| /// } |
| /// ``` |
| </span><span class="attribute">#[derive(Clone, Copy, Debug)] |
| </span><span class="kw">pub struct </span>Range<X> { |
| low: X, |
| range: X, |
| accept_zone: X, |
| } |
| |
| <span class="kw">impl</span><X: SampleRange + PartialOrd> Range<X> { |
| <span class="doccomment">/// Create a new `Range` instance that samples uniformly from |
| /// `[low, high)`. Panics if `low >= high`. |
| </span><span class="kw">pub fn </span>new(low: X, high: X) -> Range<X> { |
| <span class="macro">assert!</span>(low < high, <span class="string">"Range::new called with `low >= high`"</span>); |
| SampleRange::construct_range(low, high) |
| } |
| } |
| |
| <span class="kw">impl</span><Sup: SampleRange> Sample<Sup> <span class="kw">for </span>Range<Sup> { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>sample<R: Rng>(<span class="kw-2">&mut </span><span class="self">self</span>, rng: <span class="kw-2">&mut </span>R) -> Sup { |
| <span class="self">self</span>.ind_sample(rng) |
| } |
| } |
| <span class="kw">impl</span><Sup: SampleRange> IndependentSample<Sup> <span class="kw">for </span>Range<Sup> { |
| <span class="kw">fn </span>ind_sample<R: Rng>(<span class="kw-2">&</span><span class="self">self</span>, rng: <span class="kw-2">&mut </span>R) -> Sup { |
| SampleRange::sample_range(<span class="self">self</span>, rng) |
| } |
| } |
| |
| <span class="doccomment">/// The helper trait for types that have a sensible way to sample |
| /// uniformly between two values. This should not be used directly, |
| /// and is only to facilitate `Range`. |
| </span><span class="kw">pub trait </span>SampleRange: Sized { |
| <span class="doccomment">/// Construct the `Range` object that `sample_range` |
| /// requires. This should not ever be called directly, only via |
| /// `Range::new`, which will check that `low < high`, so this |
| /// function doesn't have to repeat the check. |
| </span><span class="kw">fn </span>construct_range(low: <span class="self">Self</span>, high: <span class="self">Self</span>) -> Range<<span class="self">Self</span>>; |
| |
| <span class="doccomment">/// Sample a value from the given `Range` with the given `Rng` as |
| /// a source of randomness. |
| </span><span class="kw">fn </span>sample_range<R: Rng>(r: <span class="kw-2">&</span>Range<<span class="self">Self</span>>, rng: <span class="kw-2">&mut </span>R) -> <span class="self">Self</span>; |
| } |
| |
| <span class="macro">macro_rules! </span>integer_impl { |
| (<span class="macro-nonterminal">$ty</span>:ty, <span class="macro-nonterminal">$unsigned</span>:ident) => { |
| <span class="kw">impl </span>SampleRange <span class="kw">for </span><span class="macro-nonterminal">$ty </span>{ |
| <span class="comment">// we play free and fast with unsigned vs signed here |
| // (when $ty is signed), but that's fine, since the |
| // contract of this macro is for $ty and $unsigned to be |
| // "bit-equal", so casting between them is a no-op & a |
| // bijection. |
| |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">fn </span>construct_range(low: <span class="macro-nonterminal">$ty</span>, high: <span class="macro-nonterminal">$ty</span>) -> Range<<span class="macro-nonterminal">$ty</span>> { |
| <span class="kw">let </span>range = (w(high <span class="kw">as </span><span class="macro-nonterminal">$unsigned</span>) - w(low <span class="kw">as </span><span class="macro-nonterminal">$unsigned</span>)).<span class="number">0</span>; |
| <span class="kw">let </span>unsigned_max: <span class="macro-nonterminal">$unsigned </span>= ::std::<span class="macro-nonterminal">$unsigned::MAX</span>; |
| |
| <span class="comment">// this is the largest number that fits into $unsigned |
| // that `range` divides evenly, so, if we've sampled |
| // `n` uniformly from this region, then `n % range` is |
| // uniform in [0, range) |
| </span><span class="kw">let </span>zone = unsigned_max - unsigned_max % range; |
| |
| Range { |
| low, |
| range: range <span class="kw">as </span><span class="macro-nonterminal">$ty</span>, |
| accept_zone: zone <span class="kw">as </span><span class="macro-nonterminal">$ty</span>, |
| } |
| } |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>sample_range<R: Rng>(r: <span class="kw-2">&</span>Range<<span class="macro-nonterminal">$ty</span>>, rng: <span class="kw-2">&mut </span>R) -> <span class="macro-nonterminal">$ty </span>{ |
| <span class="kw">loop </span>{ |
| <span class="comment">// rejection sample |
| </span><span class="kw">let </span>v = rng.gen::<<span class="macro-nonterminal">$unsigned</span>>(); |
| <span class="comment">// until we find something that fits into the |
| // region which r.range evenly divides (this will |
| // be uniformly distributed) |
| </span><span class="kw">if </span>v < r.accept_zone <span class="kw">as </span><span class="macro-nonterminal">$unsigned </span>{ |
| <span class="comment">// and return it, with some adjustments |
| </span><span class="kw">return </span>(w(r.low) + w((v % r.range <span class="kw">as </span><span class="macro-nonterminal">$unsigned</span>) <span class="kw">as </span><span class="macro-nonterminal">$ty</span>)).<span class="number">0</span>; |
| } |
| } |
| } |
| } |
| }; |
| } |
| |
| <span class="macro">integer_impl! </span>{ i8, u8 } |
| <span class="macro">integer_impl! </span>{ i16, u16 } |
| <span class="macro">integer_impl! </span>{ i32, u32 } |
| <span class="macro">integer_impl! </span>{ i64, u64 } |
| <span class="macro">integer_impl! </span>{ isize, usize } |
| <span class="macro">integer_impl! </span>{ u8, u8 } |
| <span class="macro">integer_impl! </span>{ u16, u16 } |
| <span class="macro">integer_impl! </span>{ u32, u32 } |
| <span class="macro">integer_impl! </span>{ u64, u64 } |
| <span class="macro">integer_impl! </span>{ usize, usize } |
| |
| <span class="macro">macro_rules! </span>float_impl { |
| (<span class="macro-nonterminal">$ty</span>:ty) => { |
| <span class="kw">impl </span>SampleRange <span class="kw">for </span><span class="macro-nonterminal">$ty </span>{ |
| <span class="kw">fn </span>construct_range(low: <span class="macro-nonterminal">$ty</span>, high: <span class="macro-nonterminal">$ty</span>) -> Range<<span class="macro-nonterminal">$ty</span>> { |
| Range { |
| low, |
| range: high - low, |
| accept_zone: <span class="number">0.0</span>, <span class="comment">// unused |
| </span>} |
| } |
| <span class="kw">fn </span>sample_range<R: Rng>(r: <span class="kw-2">&</span>Range<<span class="macro-nonterminal">$ty</span>>, rng: <span class="kw-2">&mut </span>R) -> <span class="macro-nonterminal">$ty </span>{ |
| r.low + r.range * rng.gen::<<span class="macro-nonterminal">$ty</span>>() |
| } |
| } |
| }; |
| } |
| |
| <span class="macro">float_impl! </span>{ f32 } |
| <span class="macro">float_impl! </span>{ f64 } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="sgx_rand" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
